Artificial turf and production method

ABSTRACT

The invention provides for a method of manufacturing artificial turf ( 1000 ). The method comprising the steps of: creating ( 100 ) a polymer mixture ( 100, 400, 500 ), wherein the polymer mixture is at least a three-phase system, wherein the polymer mixture comprises a first polymer ( 402 ), a second polymer ( 404 ), and a compatibiiizer ( 406 ), wherein the first polymer and the second polymer are immiscible, wherein the first polymer forms polymer beads ( 408 ) surrounded by the compatibiiizer within the second polymer; extruding ( 102 ) the polymer mixture into a monofilament ( 606 ); quenching ( 104 ) the monofilament; reheating ( 106 ) the monofilament; stretching ( 108 ) the reheated monofilament to deform the polymer beads into threadlike regions ( 800 ) and to form the monofilament into an artificial turf fiber ( 1004 ); incorporating ( 110 ) the artificial turf fiber into an artificial turf carpet ( 1002 ).

FIELD OF THE INVENTION

The invention relates to artificial turf and the production ofartificial turf which is also referred to as synthetic turf. Theinvention further relates to the production of fibers that imitategrass, and in particular a product and a production method forartificial turf fibers based on polymer blends and of the artificialturf carpets made from these artificial turf fibers.

BACKGROUND AND RELATED ART

Artificial turf or artificial grass is surface that is made up of fiberswhich is used to replace grass. The structure of the artificial turf isdesigned such that the artificial turf has an appearance which resemblesgrass. Typically artificial turf is used as a surface for sports such assoccer, American football, rugby, tennis, golf, for playing fields, orexercise fields. Furthermore artificial turf is frequently used forlandscaping applications.

An advantage of using artificial turf is that it eliminates the need tocare for a grass playing or landscaping surface, like regular mowing,scarifying, fertilizing and watering. Watering can be e.g. difficult dueto regional restrictions for water usage. In other climatic zones there-growing of grass and re-formation of a closed grass cover is slowcompared to the damaging of the natural grass surface by playing and/orexercising on the field. Artificial turf fields though they do notrequire a similar attention and effort to be maintained, may requiresome maintenance such as having to be cleaned from dirt and debris andhaving to be brushed regularly. This may be done to help fibers stand-upafter being stepped down during the play or exercise. Throughout thetypical usage time of 5-15 years it may be beneficial if an artificialturf sports field can withstand high mechanical wear, can resist UV, canwithstand thermal cycling or thermal ageing, can resist inter-actionswith chemicals and various environmental conditions. It is thereforebeneficial if the artificial turf has a long usable life, is durable,and keeps its playing and surface characteristics as well as appearancethroughout its usage time.

United States Patent application US 2010/0173102 A1 discloses anartificial grass that is characterized in that the material for thecladding has a hyprophilicity which is different from the hyprophilicityof the material which is used for the core.

SUMMARY

The invention provides for a method of manufacturing artificial turf inthe independent claims. Embodiments are given in the dependent claims.

In one aspect the invention provides for a method of manufacturingartificial turf carpet. The method comprises the step of creating apolymer mixture. The polymer mixture as used herein encompasses amixture of different types of polymers and also possibly with variousadditives added to the polymer mixture. The term ‘polymer mixture’ mayalso be replaced with the term ‘master batch’ or ‘compound batch’. Thepolymer mixture is at least a three-phase system. A three-phase systemas used herein encompasses a mixture that separates out into at leastthree distinct phases. The polymer mixture comprises a first polymer, asecond polymer, and a compatibilizer. These three items form the phasesof the three-phase system. If there are additional polymers orcompatibilizers added to the system then the three-phase system may beincreased to a four, five, or more phase system. The first polymer andthe second polymer are immiscible. The first polymer forms polymer beadssurrounded by the compatibilizer within the second polymer.

The method further comprises the step of extruding the polymer mixtureinto a monofilament. To perform this extrusion the polymer mixture mayfor instance be heated. The method further comprises the step ofquenching the monofilament. In this step the monofilament is cooled. Themethod further comprises the step of reheating the monofilament. Themethod further comprises the step of stretching the reheated filament todeform the polymer beads into thread-like regions and to form themonofilament into an artificial turf fiber. In this step themonofilament is stretched. This causes the monofilament to become longerand in the process the polymer beads are stretched and elongated.Depending upon the amount of stretching the polymer beads are elongatedmore.

The method further comprises the step of incorporating the artificialturf fiber into an artificial turf backing. In some examples theartificial turf backing is a textile or a textile matt.

The incorporation of the artificial turf fiber into the artificial turfbacking could for example be performed by tufting the artificial turffiber into an artificial turf backing and binding the tufted artificialturf fibers to the artificial turf backing. For instance the artificialturf fiber may be inserted with a needle into the backing and tufted theway a carpet may be. If loops of the artificial turf fiber are formedthen may be cut during the same step. The method further comprises thestep of binding the artificial turf fibers to the artificial turfbacking. In this step the artificial turf fiber is bound or attached tothe artificial turf backing. This may be performed in a variety of wayssuch as gluing or coating the surface of the artificial turf backing tohold the artificial turf fiber in position. This for instance may bedone by coating a surface or a portion of the artificial turf backingwith a material such as latex or polyurethane.

The incorporation of the artificial turf fiber into the artificial turfbacking could for example be performed alternatively by weaving theartificial turf fiber into artificial turf backing (or fiber mat) duringmanufacture of the artificial turf carpet. This technique ofmanufacturing artificial turf is known from United States patentapplication US 20120125474 A1.

The term ‘polymer bead’ or ‘beads’ may refer to a localized region, suchas a droplet, of a polymer that is immiscible in the second polymer. Thepolymer beads may in some instances be round or spherical oroval-shaped, but they may also be irregularly-shaped. In some instancesthe polymer bead will typically have a size of approximately 0.1 to 3micrometer, preferably 1 to 2 micrometer in diameter. In other examplesthe polymer beads will be larger. They may for instance have a size witha diameter of a maximum of 50 micrometer.

In some examples the stretched monofilament may be used directly as theartificial turf fiber. For example the monofilament could be extruded asa tape or other shape.

In other examples the artificial turf fiber may be a bundle or group ofseveral stretched monofilament fibers is in general cabled, twisted, orbundled together. In some cases the bundle is rewound with a so calledrewinding yarn, which keeps the yarn bundle together and makes it readyfor the later tufting or weaving process.

The monofilaments may for instance have a diameter of 50-600 micrometerin size. The yarn weight may typically reach 50-3000 dtex.

Embodiments may have the advantage that the second polymer and anyimmiscible polymers may not delaminate from each other. The thread-likeregions are embedded within the second polymer. It is thereforeimpossible for them to delaminate. The use of the first polymer and thesecond polymer enables the properties of the artificial turf fiber to betailored. For instance a softer plastic may be used for the secondpolymer to give the artificial turf a more natural grass-like and softerfeel. A more rigid plastic may be used for the first polymer or otherimmiscible polymers to give the artificial turf more resilience andstability and the ability to spring back after being stepped or presseddown.

A further advantage may possibly be that the thread-like regions areconcentrated in a central region of the monofilament during theextrusion process. This leads to a concentration of the more rigidmaterial in the center of the monofilament and a larger amount of softerplastic on the exterior or outer region of the monofilament. This mayfurther lead to an artificial turf fiber with more grass-likeproperties.

A further advantage may be that the artificial turf fibers have improvedlong term elasticity. This may require reduced maintenance of theartificial turf and require less brushing of the fibers because theymore naturally regain their shape and stand up after use or beingtrampled.

In another embodiment the polymer bead comprises crystalline portionsand amorphous portions. The polymer mixture was likely heated during theextrusion process and portions of the first polymer and also the secondpolymer may have a more amorphous structure or a more crystallinestructure in various regions. Stretching the polymer beads into thethread-like regions may cause an increase in the size of the crystallineportions relative to the amorphous portions in the first polymer. Thismay lead for instance to the first polymer to become more rigid thanwhen it has an amorphous structure. This may lead to an artificial turfwith more rigidity and ability to spring back when pressed down. Thestretching of the monofilament may also cause in some cases the secondpolymer or other additional polymers also to have a larger portion oftheir structure become more crystalline.

In a specific example of this the first polymer could be polyamide andthe second polymer could be polyethylene. Stretching the polyamide willcause an increase in the crystalline regions making the polyamidestiffer. This is also true for other plastic polymers.

In another embodiment the creating of the polymer mixture comprises thestep of forming a first mixture by mixing the first polymer with thecompatibilizer. The creation of the polymer mixture further comprisesthe step of heating the first mixture. The step of creating the polymermixture further comprises the step of extruding the first mixture. Thecreating of the polymer mixture further comprises the step of extrudingthe first mixture. The creation of the polymer mixture further comprisesthe steps of granulating the extruded first mixture. The creating of thepolymer mixture further comprises the step of mixing the granulatedfirst mixture with the second polymer. The creation of the polymermixture further comprises the step of heating the granulated firstmixture with the second polymer to form the polymer mixture. Thisparticular method of creating the polymer mixture may be advantageousbecause it enables very precise control over how the first polymer andcompatibilizer are distributed within the second polymer. For instancethe size or shape of the extruded first mixture may determine the sizeof the polymer beads in the polymer mixture.

In the aforementioned method of creating the polymer mixture forinstance a so called one-screw extrusion method may be used. As analternative to this the polymer mixture may also be created by puttingall of the components that make it up together at once. For instance thefirst polymer, the second polymer and the compatibilizer could be alladded together at the same time. Other ingredients such as additionalpolymers or other additives could also be put together at the same time.The amount of mixing of the polymer mixture could then be increased forinstance by using a two-screw feed for the extrusion. In this case thedesired distribution of the polymer beads can be achieved by using theproper rate or amount of mixing.

In another embodiment the polymer mixture is at least a four-phasesystem. The polymer mixture comprises at least a third polymer. Thethird polymer is immiscible with the second polymer. The third polymerfurther forms the polymer beads surrounded by the compatibilizer withinthe second polymer.

In another embodiment the creating of the polymer mixture comprises thestep of forming a first mixture by mixing the first polymer and thethird polymer with the compatibilizer. The creating of the polymermixture further comprises the step of heating the first mixture. Thecreating of the polymer mixture first comprises the step of extrudingthe first mixture. The creating of the polymer mixture further comprisesthe step of granulating the extruded first mixture. The creating of thepolymer mixture further comprises mixing the first mixture with thesecond polymer. The creating of the polymer mixture further comprisesthe step of heating the first mixture with the second polymer to formthe polymer mixture. This method may provide for a precise means ofmaking the polymer mixture and controlling the size and distribution ofthe polymer beads using two different polymers. As an alternative thefirst polymer could be used to make a granulate with the compatibilizerseparately from making the third polymer with the same or a differentcompatibilizer. The granulates could then be mixed with the secondpolymer to make the polymer mixture.

As an alternative to this the polymer mixture could be made by addingthe first polymer, a second polymer, the third polymer and thecompatibilizer all together at the same time and then mixing them morevigorously. For instance a two-screw feed could be used for theextruder.

In another embodiment the third polymer is a polar polymer.

In another embodiment the third polymer is polyamide.

In another embodiment the third polymer is polyethylene terephthalate,which is also commonly abbreviated as PET.

In another embodiment the third polymer is polybutylene terephthalate,which is also commonly abbreviated as PBT.

In another embodiment the polymer mixture comprises between 1% and 30%by weight the first polymer and the third polymer combined. In thisexample the balance of the weight may be made up by such components asthe second polymer, the compatibilizer, and any other additionaladditives put into the polymer mixture.

In another embodiment the polymer mixture comprises between 1 and 20% byweight of the first polymer and the third polymer combined. Again, inthis example the balance of the weight of the polymer mixture may bemade up by the second polymer, the compatibilizer, and any otheradditional additives.

In another embodiment the polymer mixture comprises between 5% and 10%by weight of the first polymer and the third polymer combined. Again inthis example the balance of the weight of the polymer mixture may bemade up by the second polymer, the compatibilizer, and any otheradditional additives.

In another embodiment the polymer mixture comprises between 1% and 30%by weight the first polymer. In this example the balance of the weightmay be made up for example by the second polymer, the compatibilizer,and any other additional additives.

In another embodiment the polymer mixture comprises between 1% and 20%by weight of the first polymer. In this example the balance of theweight may be made up by the second polymer, the compatibilizer, and anyother additional additives mixed into the polymer mixture.

In another embodiment the polymer mixture comprises between 5% and 10%by weight of the first polymer. This example may have the balance of theweight made up by the second polymer, the compatibilizer, and any otheradditional additives mixed into the polymer mixture.

In another embodiment the first polymer is a polar polymer.

In another embodiment the first polymer is polyamide.

In another embodiment the first polymer is polyethylene terephthalatewhich is commonly known by the abbreviation PET.

In another embodiment the first polymer is polybutylene terephthalatewhich is also known by the common abbreviation PBT.

In another embodiment the second polymer is a non-polar polymer.

In another embodiment the second polymer is polyethylene.

In another embodiment the second polymer is polypropylene.

In another embodiment the second polymer is a mixture of theaforementioned polymers which may be used for the second polymer.

In another embodiment the compatibilizer is any one of the following: amaleic acid grafted on polyethylene or polyamide; a maleic anhydridegrafted on free radical initiated graft copolymer of polyethylene, SEBS,EVA, EPD, or polyproplene with an unsaturated acid or its anhydride suchas maleic acid, glycidyl methacrylate, ricinoloxazoline maleinate; agraft copolymer of SEBS with glycidyl methacrylate, a graft copolymer ofEVA with mercaptoacetic acid and maleic anhydride; a graft copolymer ofEPDM with maleic anhydride; a graft copolymer of polypropylene withmaleic anhydride; a polyolefin-graft-polyamidepolyethylene or polyamide;and a polyacrylic acid type compatibalizer.

In another embodiment the polymer mixture comprises between 80-90% byweight of the second polymer. In this example the balance of the weightmay be made up by the first polymer, possibly the second polymer if itis present in the polymer mixture, the compatibilizer, and any otherchemicals or additives added to the polymer mixture.

In another embodiment the polymer mixture further comprises any one ofthe following: a wax, a dulling agent, a ultraviolet stabilizer, a flameretardant, an anti-oxidant, a pigment, and combinations thereof. Theselisted additional components may be added to the polymer mixture to givethe artificial turf fibers other desired properties such as being flameretardant, having a green color so that the artificial turf more closelyresembles grass and greater stability in sunlight.

In another embodiment creating the artificial turf fiber comprisesweaving the monofilament into the artificial turf fiber. That is to sayin some examples the artificial turf fiber is not a single monofilamentbut a combination of a number of fibers.

In another embodiment the artificial turf fiber is a yarn.

In another embodiment the method further comprises bundling stretchedmonofilaments together to create the artificial turf fiber.

In another embodiment the method further comprises weaving, bundling, orspinning multiple monofilaments together to create the artificial turffiber. Multiple, for example 4 to 8 monofilaments, could be formed orfinished into a yarn.

In another aspect the invention provides for an artificial turfmanufacture according to any one of the aforementioned methods.

In another aspect the invention provides for an artificial turfcomprising an artificial turf backing and artificial turf fiber tuftedinto the artificial turf backing. The artificial turf backing may forinstance be a textile or other flat structure which is able to havefibers tufted into it. The artificial turf fiber comprises at least onemonofilament. Each of the at least one monofilament comprises a firstpolymer in the form of thread-like regions. Each of the at least onemonofilament comprises a second polymer, wherein the thread-like regionsare embedded in the second polymer. Each of the at least onemonofilaments comprises a compatibilizer surrounding each of thethread-like regions and separating the at least one first polymer fromthe second polymer. This artificial turf may have the advantage of beingextremely durable because the thread-like regions are embedded withinthe second polymer via a compatibilizer. They therefore do not have theability to delaminate. Having the second polymer surrounding the firstpolymer may provide for a stiff artificial turf that is soft and feelssimilar to real turf. The artificial turf as described herein isdistinct from artificial turf which is coextruded. In coextrusion a coreof typically 50 to 60 micrometer may be surrounded by an outer cover orsheathing material which has a diameter of approximately 200 to 300micrometer in diameter. In this artificial turf there is a large numberof thread-like regions of the first polymer. The thread-like regions maynot continue along the entire length of the monofilament. The artificialturf may also have properties or features which are provided for by anyof the aforementioned method steps.

In another embodiment the thread-like regions have a diameter of lessthan 20 micrometer.

In another embodiment the thread-like regions have a diameter of lessthan 10 micrometer.

In another embodiment the thread-like regions have a diameter of between1 and 3 micrometer.

In another embodiment the artificial turf fiber extends a predeterminedlength beyond the artificial turf backing. The thread-like regions havea length less than one half of the predetermined length.

In another embodiment the thread-like regions have a length of less than2 mm.

It is understood that one or more of the aforementioned embodiments ofthe invention may be combined as long as the combined embodiments arenot mutually exclusive.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following embodiments of the invention are explained in greaterdetail, by way of example only, making reference to the drawings inwhich:

FIG. 1 shows a flowchart which illustrates an example of a method ofmanufacturing artificial turf;

FIG. 2 shows a flowchart which illustrates one method of creating thepolymer mixture;

FIG. 3 shows a flowchart which illustrates a further example of how tocreate a polymer mixture;

FIG. 4 shows a diagram which illustrates a cross-section of a polymermixture;

FIG. 5 shows a further example of a polymer mixture;

FIG. 6 illustrates the extrusion of the polymer mixture into amonofilament;

FIG. 7 shows a cross-section of a small segment of the monofilament;

FIG. 8 illustrates the effect of stretching the monofilament;

FIG. 9 shows an electron microscope picture of a cross-section of astretched monofilament; and

FIG. 10 shows an example of a cross-section of an example of artificialturf.

DETAILED DESCRIPTION

Like numbered elements in these figures are either equivalent elementsor perform the same function. Elements which have been discussedpreviously will not necessarily be discussed in later figures if thefunction is equivalent.

FIG. 1 shows a flowchart which illustrates an example of a method ofmanufacturing artificial turf. First in step 100 a polymer mixture iscreated. The polymer mixture is at least a three-phase system. Thepolymer mixture comprises a first polymer. The polymer mixture furthercomprises a second polymer and a compatibilizer. The first polymer andthe second polymer are immiscible. In other examples there may beadditional polymers such as a third, fourth, or even fifth polymer thatare also immiscible with the second polymer. There also may beadditional compatibilizers which are used either in combination with thefirst polymer or the additional third, fourth, or fifth polymer. Thefirst polymer forms polymer beads surrounded by the compatibilizer. Thepolymer beads may also be formed by additional polymers which are notmiscible in the second polymer.

The polymer beads are surrounded by the compatibilizer and are withinthe second polymer or mixed into the second polymer. In the next step102 the polymer mixture is extruded into a monofilament. Next in step104 the monofilament is quenched or rapidly cooled down. Next in step106 the monofilament is reheated. In step 108 the reheated monofilamentis stretched to deform the polymer beads into thread-like regions and toform the monofilament into the artificial turf fiber. Additional stepsmay also be performed on the monofilament to form the artificial turffiber. For instance the monofilament may be spun or woven into a yarnwith desired properties. Next in step 110 the artificial turf fiber isincorporated into an artificial turf backing. Step 110 could for examplebe, but is not limited to, tufting or weaving the artificial turf fiberinto the artificial turf backing. Then in step 112 the artificial turffibers are bound to the artificial turf backing. For instance theartificial turf fibers may be glued or held in place by a coating orother material. Step 112 is an optional step. For example if theartificial turf fibers are woven into the artificial turf backing step112 may not need to be performed.

FIG. 2 shows a flowchart which illustrates one method of creating thepolymer mixture. In this example the polymer mixture is a three-phasesystem and comprises the first polymer, a second polymer and thecompatibilizer. The polymer mixture may also comprise other things suchas additives to color or provide flame or UV-resistance or improve theflowing properties of the polymer mixture. First in step 200 a firstmixture is formed by mixing the first polymer with the compatibilizer.Additional additives may also be added during this step. Next in step202 the first mixture is heated. Next in step 204 the first mixture isextruded. Then in step 206 the extruded first mixture is then granulatedor chopped into small pieces. Next in step 208 the granulated firstmixture is mixed with the second polymer. Additional additives may alsobe added to the polymer mixture at this time. Finally in step 210 thegranulated first mixture is heated with the second polymer to form thepolymer mixture. The heating and mixing may occur at the same time.

FIG. 3 shows a flowchart which illustrates a further example of how tocreate a polymer mixture 100. In this example the polymer mixtureadditionally comprises at least a third polymer. The third polymer isimmiscible with the second polymer and the polymer mixture is at least afour-phase system. The third polymer further forms the polymer beadssurrounded by the compatibilizer with the second polymer. First in step300 a first mixture is formed by mixing the first polymer and the thirdpolymer with the compatibilizer. Additional additives may be added tothe first mixture at this point. Next in step 302 the first mixture isheated. The heating and the mixing of the first mixture may be done atthe same time. Next in step 304 the first mixture is extruded. Next instep 306 the extruded first mixture is granulated or chopped into tinypieces. Next in step 308 the first mixture is mixed with the secondpolymer. Additional additives may be added to the polymer mixture atthis time. Then finally in step 310 the heated first mixture and thesecond polymer are heated to form the polymer mixture. The heating andthe mixing may be done simultaneously.

FIG. 4 shows a diagram which illustrates a cross-section of a polymermixture 400. The polymer mixture 400 comprises a first polymer 402, asecond polymer 404, and a compatibilizer 406. The first polymer 402 andthe second polymer 404 are immiscible. The first polymer 402 is lessabundant than the second polymer 404. The first polymer 402 is shown asbeing surrounded by compatibilizer 406 and being dispersed within thesecond polymer 404. The first polymer 402 surrounded by thecompatibilizer 406 forms a number of polymer beads 408. The polymerbeads 408 may be spherical or oval in shape or they may also beirregularly-shaped depending up on how well the polymer mixture is mixedand the temperature. The polymer mixture 400 is an example of athree-phase system. The three phases are the regions of the firstpolymer 402. The second phase region is the compatibilizer 406 and thethird phase region is the second polymer 404. The compatibilizer 406separates the first polymer 402 from the second polymer 406.

FIG. 5 shows a further example of a polymer mixture 500. The exampleshown in FIG. 5 is similar to that shown in FIG. 4 however, the polymermixture 500 additionally comprises a third polymer 502. Some of thepolymer beads 408 are now comprised of the third polymer 502. Thepolymer mixture 500 shown in FIG. 5 is a four-phase system. The fourphases are made up of the first polymer 402, the second polymer 404, thethird polymer 502, and the compatibilizer 406. The first polymer 402 andthe third polymer 502 are not miscible with the second polymer 404. Thecompatibilizer 406 separates the first polymer 402 from the secondpolymer 404 and the third polymer 502 from the second polymer 404.

In this example the same compatibilizer 406 is used for both the firstpolymer 402 and the third polymer 502. In other examples a differentcompatibilizer 406 could be used for the first polymer 402 and the thirdpolymer 502.

FIG. 6 illustrates the extrusion of the polymer mixture into amonofilament. Shown is an amount of polymer mixture 600. Within thepolymer mixture 600 there is a large number of polymer beads 408. Thepolymer beads 408 may be made of one or more polymers that is notmiscible with the second polymer 404 and is also separated from thesecond polymer 404 by a compatibilizer. A screw, piston or other deviceis used to force the polymer mixture 600 through a hole 604 in a plate602. This causes the polymer mixture 600 to be extruded into amonofilament 606. The monofilament 606 is shown as containing polymerbeads 408 also. The second polymer 404 and the polymer beads 408 areextruded together. In some examples the second polymer 404 will be lessviscous than the polymer beads 408 and the polymer beads 408 will tendto concentrate in the center of the monofilament 606. This may lead todesirable properties for the final artificial turf fiber as this maylead to a concentration of the thread-like regions in the core region ofthe monofilament 606.

FIG. 7 shows a cross-section of a small segment of the monofilament 606.The monofilament is again shown as comprising the second polymer 404with the polymer beads 408 mixed in. The polymer beads 408 are separatedfrom the second polymer 404 by compatibilizer 406 which is not shown. Toform the thread-like structures a section of the monofilament 606 isheated and then stretched along the length of the monofilament 606. Thisis illustrated by the arrows 700 which show the direction of thestretching.

FIG. 8 illustrates the effect of stretching the monofilament 606. InFIG. 8 an example of a cross-section of a stretched monofilament 606 isshown. The polymer beads 408 in FIG. 7 have been stretched intothread-like structures 800. The amount of deformation of the polymerbeads 408 would be dependent upon how much the monofilament 606′ hasbeen stretched.

Examples may relate to the production of artificial turf which is alsoreferred to as synthetic turf. In particular, the invention relates tothe production of fibers that imitate grass. The fibers are composed offirst and second polymers that are not miscible and differ in materialcharacteristics as e.g. stiffness, density, polarity and acompatibilizer.

In a first step, a first polymer is mixed with the a compatibilizer.Color pigments, UV and thermal stabilizers, process aids and othersubstances that are as such known from the art can be added to themixture. This may result in granular material which consist of a twophase system in which the first polymer is surrounded by thecompatibilizer.

In a second step, a three-phase system is formed by adding the secondpolymer to the mixture whereby in this example the quantity of thesecond polymer is about 80-90 mass percent of the three-phase system,the quantities of the first polymer being 5% to 10% by mass and of thecompatibilizer being 5% to 10% by mass. Using extrusion technologyresults in a mixture of droplets or of beads of the first polymersurrounded by the compatibilizer that is dispersed in the polymer matrixof the second polymer. In a practical implementation a so called masterbatch including granulate of the first polymer and the compatibilizer isformed. The master batch may also be referred to as a “polymer mixture”herein. The granulate mix is melted and a mixture of the first polymerand the compatibilizer is formed by extrusion. The resulting strands arecrushed into granulate. The resultant granulate and granulate of thesecond polymer are then used in a second extrusion to produce the thickfiber which is then stretched into the final fiber.

The melt temperature used during extrusions is dependent upon the typeof polymers and compatibilizer that is used. However the melttemperature is typically between 230° C. and 280° C.

A monofilament, which can also be referred to as a filament orfibrillated tape, is produced by feeding the mixture into an fiberproducing extrusion line. The melt mixture is passing the extrusiontool, i.e., a spinneret plate or a wide slot nozzle, forming the meltflow into a filament or tape form, is quenched or cooled in a water spinbath, dried and stretched by passing rotating heated godets withdifferent rotational speed and/or a heating oven.

The monofilament or type is then annealed online in a second steppassing a further heating oven and/or set of heated godets.

By this procedure the beads or droplets of polymer 1, surrounded by thecompatibilizer are stretched into longitudinal direction and form smallfiber like, linear structures which stay however completely embeddedinto the polymer matrix of the second polymer.

FIG. 9 shows a microscopic picture of a cross-section of a stretchedmonofilament manufactured using an example of a method described above.The horizontal white streaks within the stretched monofilament 606 arethe thread-like structures 800. Several of these thread-like structuresare labeled 800. The thread-like structures 800 can be shown as formingsmall linear structures of the first polymer within the second polymer.

The resultant fiber may have multiple advantages, namely softnesscombined with durability and long term elasticity. In case of differentstiffness and bending properties of the polymers the fiber can show abetter resilience (this means that once a fiber is stepped down it willspring back) In case of a stiff first polymer, the small linear fiberstructures built in the polymer matrix are providing a polymerreinforcement of the fiber.

Delimitation due to the composite formed by the first and secondpolymers is prevented due to the fact that the short fibers of thesecond polymer are embedded in the matrix given by the first polymer.Moreover, complicated coextrusion, requiring several extrusion heads tofeed one complex spinneret tool is not needed.

The first polymer can be a polar substance, such as polyamide, whereasthe second polymer can be a non-polar polymer, such as polyethylene.Alternatives for the first polymer are polyethylene terephthalate (PET)or polybutylene terephthalate (PBT) for the second polymerpolypropylene. Finally a material consisting of 3 polymers is possible(e.g. PET, PA and PP, with PP creating the matrix and the other creatingindependent from each other fibrous linear structures. Thecompatibilizer can be a maleic anhydride grafted on polyethylene orpolyamide.

FIG. 10 shows an example of a cross-section of an example of artificialturf 1000. The artificial turf 1000 comprises an artificial turf backing1002. Artificial turf fiber 1004 has been tufted into the artificialturf backing 1002. On the bottom of the artificial turf backing 1002 isshown a coating 1006. The coating may serve to bind or secure theartificial turf fiber 1004 to the artificial turf backing 1002. Thecoating 1006 may be optional. For example the artificial turf fibers1004 may be alternatively woven into the artificial turf backing 1002.Various types of glues, coatings or adhesives could be used for thecoating 1006. The artificial turf fibers 1004 are shown as extending adistance 1008 above the artificial turf backing 1002. The distance 1008is essentially the height of the pile of the artificial turf fibers1004. The length of the thread-like regions within the artificial turffibers 1004 is half of the distance 1008 or less.

LIST OF REFERENCE NUMERALS

-   100 create a polymer mixture-   102 extrude the polymer mixture into a monofilament-   104 quench the monofilament-   106 reheat the monofilament-   108 stretch the reheated monofilament to deform the polymer beads    into threadlike regions and to form the monofilament into an    artificial turf fiber-   110 incorporate the artificial turf fiber into an artificial turf    carpet-   112 optionally bind the artificial turf fibers to the artificial    turf carpet-   200 form a first mixture by mixing the first polymer with the    compatibilizer-   202 heat the first mixture-   204 extrude the first mixture-   206 granulate the extruded first mixture-   208 mix the granulated first mixture with the second polymer-   210 heat the granulated first mixture with the second polymer to    form the polymer mixture-   300 form a first mixture by mixing the first polymer and the third    polymer with the compatibilizer-   302 heat the first mixture-   304 extrude the first mixture-   306 granulate the extruded first mixture-   308 mix the first mixture with the second polymer-   310 heat the mixed first mixture with the second polymer to form the    polymer mixture-   400 polymer mixture-   402 first polymer-   404 second polymer-   406 compatibilizer-   408 polymer bead-   500 polymer mixture-   502 third polymer-   600 polymer mixture-   602 plate-   604 hole-   606 monofilament-   606′ stretched monofilament-   700 direction of stretching-   800 threadlike structures-   1000 artificial turf-   1002 artificial turf carpet-   1004 artificial turf fiber (pile)-   1006 coating-   1008 height of pile

1. A method of manufacturing artificial turf (1000), the methodcomprising the steps of: creating (100) a polymer mixture (100, 400,500), wherein the polymer mixture is at least a three-phase system,wherein the polymer mixture comprises a first polymer (402), a secondpolymer (404), and a compatibilizer (406), wherein the first polymer andthe second polymer are immiscible, wherein the first polymer formspolymer beads (408) surrounded by the compatibilizer within the secondpolymer; extruding (102) the polymer mixture into a monofilament (606);quenching (104) the monofilament; reheating (106) the monofilament;stretching (108) the reheated monofilament to deform the polymer beadsinto threadlike regions (800) and to form the monofilament into anartificial turf fiber (1004); incorporating (110) the artificial turffiber into an artificial turf backing (1002).
 2. The method of claim 1,wherein the polymer bead comprises crystalline portions and amorphousportions, wherein stretching the polymer beads into threadlike regionscauses an increase in the size of the crystalline portions relative tothe amorphous portions.
 3. The method of claim 1 or 2, wherein thecreating of the polymer mixture comprises the steps of: forming (200) afirst mixture by mixing the first polymer with the compatibilizer;heating (202) the first mixture; extruding (204) the first mixture;granulating (206) the extruded first mixture; mixing (208) thegranulated first mixture with the second polymer; and heating (210) thegranulated first mixture with the second polymer to form the polymermixture.
 4. The method of claim 1 or 2, wherein the polymer mixture isat least a four phase system, wherein the polymer mixture comprises atleast a third polymer (502), wherein the third polymer is immisciblewith the second polymer, wherein the third polymer further forms thepolymer beads surrounded by the compatibilizer within the secondpolymer.
 5. The method of claim 4, wherein the creating of the polymermixture comprises the steps of: forming (300) a first mixture by mixingthe first polymer and the third polymer with the compatibilizer; heating(302) the first mixture; extruding (304) the first mixture; granulating(306) the extruded first mixture; mixing (308) the first mixture withthe second polymer; and heating (310) the mixed first mixture with thesecond polymer to form the polymer mixture.
 6. The method of claim 4 or5, wherein the third polymer is a polar polymer.
 7. The method of anyone of the preceding claims, wherein the third polymer is any one of thefollowing: polyamide, polyethylene terephthalate (PET), and polybutyleneterephthalate (PBT).
 8. The method of any one of the preceding claims,wherein the polymer mixture comprises 1 to 30 percent by weight thefirst polymer and the third polymer combined.
 9. The method of any oneof claims 1 to 7, wherein the polymer mixture comprises 1 to 20 percentby weight the first polymer and the third polymer combined.
 10. Themethod of any one of claims 1 to 7, wherein the polymer mixturecomprises 5 to 10 percent by weight the first polymer and the thirdpolymer combined.
 11. The method of claim 1, 2, or 3, wherein thepolymer mixture comprises 1 to 30 percent by weight the first polymer.12. The method of claim 1, 2, or 3, wherein the polymer mixturecomprises 1 to 20 percent by weight the first polymer.
 13. The method ofclaim 1, 2, or 3, wherein the polymer mixture comprises 5 to 10 percentby weight the first polymer.
 14. The method of any one of the precedingclaims, wherein the first polymer is a polar polymer.
 15. The method ofany one of the preceding claims, wherein the first polymer is any one ofthe following: polyamide, polyethylene terephthalate (PET), andpolybutylene terephthalate (PBT).
 16. The method of any one of thepreceding claims, wherein the second polymer is a non-polar polymer. 17.The method of any one of the preceding claims, wherein the secondpolymer is any one of the following: polyethylene, polypropylene, and amixture thereof.
 18. The method of any one of the preceding claims,wherein the compatibilizer is any one of the following: a maleic acidgrafted on polyethylene or polyamide; a maleic anhydride grafted on freeradical initiated graft copolymer of polyethylene, SEBS, EVA, EPD, orpolyproplene with an unsaturated acid or its anhydride such as maleicacid, glycidyl methacrylate, ricinoloxazoline maleinate; a graftcopolymer of SEBS with glycidyl methacrylate, a graft copolymer of EVAwith mercaptoacetic acid and maleic anhydride; a graft copolymer of EPDMwith maleic anhydride; a graft copolymer of polypropylene with maleicanhydride; a polyolefin-graft-polyamidepolyethylene or polyamide; and apolyacrylic acid type compatibilizer.
 19. The method of any one of thepreceding claims, wherein the polymer mixture comprises 80 to 90 percentby weight the second polymer.
 20. The method of any one of the precedingclaims, wherein the polymer mixture further comprises any one of thefollowing: a wax, a dulling agent, a UV stabilizer, a flame retardant,an anti-oxidant, a pigment, and combinations thereof.
 21. The method ofany one of the preceding claims, wherein creating the artificial turffiber comprises forming the stretched monofilament into a yarn.
 22. Themethod of any one of the preceding claims, wherein creating theartificial turf fiber comprises weaving, spinning, twisting, rewinding,and/or bundling the stretched monofilament into the artificial turffiber.
 23. The method of any one of the preceding claims, whereinincorporating the artificial turf fiber into the artificial turf backingcomprises: tufting the artificial turf fiber into the artificial turfbacking and binding the artificial turf fibers to the artificial turfbacking.
 24. The method of any one of claims 1 through 22, whereinincorporating the artificial turf fiber into the artificial turf backingcomprises weaving the artificial turf fiber into the artificial turfbacking.
 25. A artificial turf manufactured according to the method ofany one of the preceding claims.
 26. An artificial turf (1000)comprising an artificial turf textile backing (1002) and artificial turffiber (1004) incorporated into the artificial turf backing, wherein theartificial turf fiber comprises at least one monofilament, wherein eachof the at least one monofilament comprises: a first polymer (402) in theform of threadlike regions (800); a second polymer (404), wherein thethreadlike regions are embedded in the second polymer, wherein the firstpolymer is immiscible in the second polymer; a compatibilizer (406)surrounding each of the threadlike regions and separating the at leastone first polymer from the second polymer.
 27. The artificial turf ofclaim 26, wherein the threadlike regions have a diameter less than 50micrometers.
 28. The artificial turf of claim 26, wherein the threadlikeregions have a diameter less than 10 micrometers.
 29. The artificialturf of claim 26, wherein the threadlike regions have a diameter ofbetween 1 and 3 micrometers.
 30. The artificial turf of any one ofclaims 27 to 30, wherein the artificial turf fiber extends apredetermined length (1008) beyond the artificial turf backing, andwherein threadlike regions have a length less than one half of thepredetermined length.
 31. The artificial turf of any one of claims 27 to31, wherein the threadlike regions have a length less than 2 mm.